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ERIC Number: ED447167
Record Type: Non-Journal
Publication Date: 2000
Pages: 48
Abstractor: N/A
Reference Count: N/A
ISBN: N/A
ISSN: N/A
The Effect of Omitted Responses on Ability Estimation in IRT.
De Ayala, R. J.; Plake, Barbara S.; Impara, James C.; Kozmicky, Michelle
This study investigated the effect on examinees' ability estimate under item response theory (IRT) when they are presented an item, have ample time to answer the item, but decide not to respond to the item. Simulation data were modeled on an empirical data set of 25,546 examinees that was calibrated using the 3-parameter logistic model. The study was conducted in three phases. Phase 1 was an exploratory study comparing the various estimation methods under different conditions. Methods compared were the Biweight, expected a posteriori (EAP), and maximum likelihood estimation (MLE) methods. Phase 2, based on Phase 1 results, examined a modified EAP approach. The third phase examined the use of R. Bock's 1972 nominal response (NR) model for handling omission data. Results seem to indicate that omits should not be treated as incorrect. It also appears that ignoring omits can have a greater impact on thetas using certain estimation approaches (e.g., MLE) than with others. To the extent that a model with a pseudo-guessing parameter more accurately describes the data than a model without one, then the use of the NR model may not produce results comparable to those seen here. (Contains 5 tables, 10 figures, and 14 references.) (SLD)
Publication Type: Reports - Research; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A